1. Field of the Invention
The present invention relates to a portable ultrasonic detector, and more particularly, to a portable ultrasonic flaw detector that obtains position information by use of an encoder unit, that is portable and this is capable of accurately detecting defects within an object to be inspected by displaying images showing the inner state of the inspected object based on data for A-scope display and data of the position information.
2. Description of the Related Art
In an ultrasonic detector, an ultrasonic probe is placed on a surface of an object to be inspected and is moved on the surface in a specific direction. The probe emits pulses of ultrasonic waves to the object periodically and receives echoes of the ultrasonic waves returned from the inside of the object in order to detect waveform information of the echoes. The echo waveform information is stored in a waveform memory as digital data. According to the ultrasonic detector, A-scope images showing waveforms such as the echoes of defects and the like are displayed on a screen of a display section by use of the data that is read out from the waveform memory at a suitable timing. Further, inner scope images showing the inside of the object, that is, B-scope images or C-scope images may be indicated on the display screen by combining the A-scope images with moved distance information (position information) of the probe.
Conventional ultrasonic detectors configured so that the B-scope images or the C-scope images can be displayed are mainly of the set-up type. The set-up type ultrasonic detectors have a structure such that the object to be inspected is placed on a sample table of a detector body and the probe supported by a moving mechanism to be opposite to the object is moved so as to scan it. The moving mechanism is provided with a measuring unit for measuring a moved amount of the probe. When making the above-mentioned images, data with regard to the moved amount, which is obtained by the measuring unit, is used.
Also, when detecting defects such as cracks within a welded member and the like, an angle beam method has been generally used. This angle beam method is such that, while moving the probe in the specific direction along the surface of the object, the probe emits the ultrasonic pulses toward the inside of the object in a direction inclined at an angle and detects the reflected echoes returned from the inside of the object. According to the angle beam method, if there is a defect such as a crack in a depth direction or a hollow within the object, both the upper and lower ends of the defect can be detected, and a shape or a type and the like of the defect can be evaluated because the angle beam method makes it possible to evaluate a size of the defect by measuring the size.
While using the conventional portable ultrasonic detector to make the A-scope images, a measurement operator (an inspector) carries it to the spot where the object exists and holds the probe thereof with his hand, and puts and moves it on the surface of the object in a manually operated mode. Since the conventional portable ultrasonic detector cannot detect a moved amount of the probe structurally, it could not display the B-scope images or the images based on the data obtained by the angle beam method. However, it has also been required for the portable ultrasonic detector to be capable of making/displaying B-scope images or the images based on the angle beam method, and further to be capable of simplifying acquisition of the defect echo waveforms by use of the position information of the probe, which is obtained by a measuring unit for measuring the moved amount of the probe, and accurately detecting positions of the defect.
It is an object of the present invention to provide a portable ultrasonic detector capable of getting echo waveforms of defects simply and improving detection accuracy on positions of the defects by enabling to carry out making/displaying B-scope images or images due to the angle beam method with simple structure.
The portable ultrasonic detector of the present invention has the following structure in order to attain the above-mentioned object.
The portable ultrasonic detector has an instrument comprised of an encoder for detecting a moved amount and a counting section (a counter) for counting the moved amount signal outputted from the encoder, as a means for obtaining position information of an ultrasonic probe. The device body of the detector includes the counting section on its main board. When moving the ultrasonic probe on the surface of the object on the occasion of the inspection, the moved amount of the ultrasonic probe is measured. The measured moved amount of the ultrasonic probe is sent to an arithmetic processing section of the device body. Also, the ultrasonic detector detects A-scope data when scanning the inspected object with the ultrasonic probe, and executes the predetermined processing by using the data.
The aforementioned ultrasonic detector has a structure that combines the A-scope data and the moved distance data of the ultrasonic probe to make an inner scope image (B-scope image and the like). When repeatedly scanning the same spot of the object with the ultrasonic probe in order to make the B-scope image, etc. and display them on a display section, peaks of defect echo waves are stored in memory in groups, and further two defect images or more are displayed on the B-scope image.
In the aforementioned structure, when repeatedly scanning the same spot of the object, concerning the defect echo waves generated on the A-scope on the occasion of each scanning action, the peak is detected and memorized whenever carrying out the scanning action. For example, when drawing the B-scope, two defect images or more are displayed per defect. Thus, the ultrasonic detector is configured to generate storage-type B-scope images on a display screen. Thereby, defect images can be evaluated in detail and the defect position can be detected accurately.
In the aforementioned structure, further, when carrying out an angle beam method, the inner scope image is made and displayed. In the arithmetic processing section, a plurality of A-scope data, which can be obtained when moving the ultrasonic probe in a direction different from the movable direction of the encoder for the scanning action, are stored in groups in a memory thereof. When displaying the images, a display means displays the image showing the inner state of the object by use of the data stored in the arithmetic processing section.
When carrying out the angle beam method for inspecting the defect generally, this inspection is carried out while confirming a depth direction or a width direction by moving the ultrasonic probe repeatedly with a short distance in a direction substantially perpendicular to an actual scanning direction (the movable direction of the encoder). Thus, defect echoes (the A-scope data) obtained when operating the ultrasonic probe repeatedly with the short distance are stored in groups, and thereby two dimensional information is stored (the information concerning the width and depth of the defect), and when the image is displayed, the accurate position and shape of the defect can be detected.
In particular, it is required for the portable ultrasonic detector to carry out the inspection in places with undesirable environment by moving the angle probe (doing the scanning action of the angle probe) bit by bit manually. The environment for the inspection is very poor. In case of such an inspection, it is difficult for an inspector with less experience to get available images, in comparison with the experienced inspector. Therefore, the ultrasonic detector of the present invention is provided with the structure or means for indicating a criteria useful for judging whether the produced images are based on the proper inspection or not, or whether the manual scanning operation of the ultrasonic probe is proper or not.